The end is all but nigh for Mother Earth's inhabitants unless drastic measures are soon taken: that's the rueful prognostication delivered by Lovelock (Gaia: A New Look at Life on Earth ), intuitive originator of the theory that the world is a self-regulating system that, over the eons, has been able to sustain an equilibrium between hot and cold so as to support life. Now, propelled by global warming, Lovelock says, a tipping point has almost been reached beyond which the Earth will not recover sufficiently to sustain human life comfortably. Lovelock dismisses biomass fuels, wind farms, solar energy and fuel cell innovations as technologies unlikely to mitigate greenhouse gases in time to save the planet. Instead he sees nuclear energy as the only energy source that can meet our needs in time to prevent catastrophe. Chernobyl was a calamity, he notes, but nuclear power's danger is "insignificant compared with the real threat of intolerable and lethal heatwaves" and rising sea levels that could "threaten every coastal city of the world." Lovelock's pro-nuke enthusiasm, unexpected from one of the mid-20th century's most ardent environmental thinkers, is the well-reasoned core of this urgent call for braking at the brink of global catastrophe. (Aug.)